Reprogramming of murine somatic cells in embryonic and adult fibroblast cultures to pluripotent ESC-like cells has recently been achieved by simultaneous viral transduction of four transcription factors (i.e. Oct4, cMyc, Sox2 and Klf4) together [5]. More recently, we and others have also reproduced similar findings in different murine systems (please see our preliminary results). With such proof-of-principle demonstrations, one of the next critical steps would be to translate such method into a human cell system and identify small molecules that would allow temporal and reversible manipulation to induce/enhance reprogramming. Cell-based phenotypic screens of synthetic small molecules and natural products have historically provided useful chemical ligands to modulate and study complex cellular processes, and recently provided a number of small molecules that can be used to selectively regulate stem cell fate [6]. Here we propose to develop a homogenous human neural cell system to examine reprogramming to pluripotency and implement a high throughput screen of 100,000 diverse and discrete compounds to identify small molecules that can induce/enhance programming somatic human cells back to pluripotent hESC-like cells. We will further confirm and characterize their effects and activities via various in-depth cellular/biochemical assays, and carry out structure-activity-relationship (SAR) studies of the selected hit compounds to optimize their potency and specificity. Collectively, the studies described in this proposal will provide novel chemical tools for producing unlimited amount of (autologous) pluripotent cells from differentiated/lineage-restricted cells for various applications as well as studying the underlying molecular mechanisms of pluripotency and epigenetic regulations, and may ultimately facilitate development of small molecule therapeutics to stimulate tissue/organ regeneration in vivo. Public Health Relevance: Collectively, the studies described in this proposal will provide novel chemical tools for producing unlimited amount of (autologous) pluripotent cells from differentiated/lineage-restricted cells for various applications as well as studying the underlying molecular mechanisms of pluripotency and epigenetic regulations, and may ultimately facilitate development of small molecule therapeutics to stimulate tissue/organ regeneration in vivo.